O-H stretch in phenol and its hydrogen-bonded complexes: band position and relaxation pathways

Anharmonic force fields are a suitable means for identification of vibrational degrees of freedom responsible for the peculiar shape of molecular spectra and the existence of diverse relaxation pathways. In this contribution, we investigated interactions that govern the position of the O-H stretching band in phenol and its dimers with water and ammonia. Dominant couplings are identified, and the nature of relaxation channels is analyzed. The effect of hydrogen bonding on O-H stretching motion and vibrational energy redistribution time through intra- and intermolecular interactions is studied, and possible vibrational predissociation upon O-H stretch excitation is addressed. The results based on computed anharmonic force constants are in accord with the available experimental findings.